Soak it in freshwater to keep it from corroding since the blade is iron. Bronze wont need much conserving, the handle, I dont know what it is. Keep it all in freshwater, and occasionally change out the water, so you get rid of the salt. Do that until you figure out what to do. As for reverse electrolysis, I wouldnt use caustic soda on anything, use sodium carbonate. Washing soda in the clothes washing area of the supermarket. If you cant find any, bake regular baking soda, sodium bicarbonate in an oven on a cookie pan for 1 hour at 350 degrees. It will turn into sodium carbonate. That is not damaging to you or the thing that you are trying to conserve. And use just enough voltage and current to just barely getting a slight fizz, just a slight overall fizz, next to nothing, too much and it will all dissolve. You just want to get rid of the salts, and hopefully loosen the coralline and rust.